Application service virtualization or application virtualization is layered on top of other virtualization technologies, such as storage virtualization or machine virtualization to allow computing resources to be distributed dynamically in real time. In standard computing, applications install their settings onto the host operating system, hard-coding the entire system to fit that application's needs. With application virtualization, each application brings down its own set of configurations on-demand, and executes in a way so that it sees only its own settings. This leaves the host operating system and existing settings unaltered.